Ethylene (C2H4) acts as a plant hormone which accelerates the ripening process in plants. In this regard, it is well known in the art that cyclopropenes effectively inhibit the ethylene action in plants [U.S. Pat. Nos. 5,518,988 and 6,194,350]. Of these cyclopropenes, 1-alkylcyclopropenes, represented by Formula 1 below, are very potent. In particular, 1-methylcyclopropene, a gas even at ambient temperature (b.p. ˜10° C./1 atm), advantageously, can be easily applied to agricultural products in a closed warehouse without any additional spray device or system. For this reason, 1-methylcyclopropene has been widely used to keep fruits, flowers and vegetables such as apples, pears, persimmons, plums, kiwis, tomatoes, lilies and carnations, fresh.

wherein A represents a straight-chain linkage having the formula of (CH2)mY(CH2)n in which m and n each independently represent an integer of 0 to 3, and Y each independently represents CH2, O, S or the like.
R1 represents saturated or unsaturated C3-C20 alkyl or C4-C10 aryl, furanyl, pyranyl or thiofuranyl, wherein alkyl or aryl may be substituted with fluoride, chloride, bromide, iodide, oxygen, sulfur, nitrogen, silicon, phosphorus or the like.
Generally, cyclopropenes such as cyclopropene, 1-methylcyclopropene, 1,2-dimethylcyclopropene, 1,3-dimethylcyclopropene, 1-ethylcyclopropene, 1-hexylcyclopropene and 1-octylcyclopropene are readily decomposed and their half life are thus only 0.5˜20 hours at room temperature. For this reason, it is impractical to synthesize, store and apply these compounds using a routine method known to the agrochemical industry. The decomposing process of these cyclopropenes is a dimerization reaction in which two molecules of cyclopropenes combine each other.
Accordingly, these cyclopropenes are much more stable in a dilute state. For example, 1-methylcyclopropene (b.p. ˜10° C./1 atm) is so unstable that it may explode at room temperature when it is purified at a high concentration. However, the half life for 1,000 ppm (v/v) or less concentration of 1-methylcyclopropene is 10 days or longer at room temperature. Furthermore, 1-methylcyclopropene can be stably stored for one year or more, when the individual molecules can be thoroughly separated using α-cyclodextrin. This method has been actually utilized in an area to store agricultural products for a long time [U.S. Pat. Nos. 6,017,849, 6,426,319, 6,444,619, 6,548,448, 6,762,153 and 6,953,540].
Meanwhile, rather than the method for storing 1-methylcyclopropene with low stability, a method for preparing 1-methylcyclopropene in situ and for immediately using the same has been also utilized in the area to store agricultural products and crops. For example, the inventor of the present invention (Korean Patent Application No. 2006-0112039) has suggested a method and an apparatus for directly preparing 1-methylcyclopropene in situ and treating plants with the same. This application discloses the preparation of 1-methylcyclopropene via the reaction of β-halocyclopropylsilane or its chemical equivalents thereof with a fluoride (F−). This method relates to a method for preparing a highly volatile compound such as 1-methylcyclopropene in situ and immediately treating agricultural products with the same which is considerably effective when agricultural products are treated primarily in an independent warehouse or an additional closed treatment area.
However, because these methods are limited to only utilizing highly volatile substances such as 1-methylcyclopropene in closed areas, they are disadvantageously not suitable for applying a variety of 1-alkylcyclopropenes to agricultural products in open areas such as rice paddies, fields, meadows, orchards, forests and large greenhouses rather than closed areas.
Conventional agrochemical agents are applied to plants via a series of processes (that is, processes such as synthesis, formulation or spraying of agrochemical agents) including (i) the synthesis of an active ingredient, (ii) the formulation of the same using a surfactant, a stabilizing agent or the like and (iii) the spray of the same to agricultural produces in rice paddies, fields, orchards, farms, forests or the like. These processes commonly require from one or two months at minimum to a year or longer at maximum.
However, as mentioned above, 1-alkylcyclopropenes are readily decomposed due to low chemical stability thereof and desired effects cannot be obtained via a typical process for preparing and treating general agrochemical agents such as pesticides. Consequently, ‘a method for storing 1-alkylcyclopropenes at an ultra-cold condition (−50° C. or below)’ or ‘a method for storing 1-alkylcyclopropenes by encapsulating the same to a substance such as cyclodextrin’ is inevitable to apply 1-alkylcyclopropenes to agricultural produces or plants in fields.